Several condos have their own gym that can only be used by the residents. There are also general outdoor gyms in different parts of the area, e.g. Next to the sports field in Kram.
The following gyms are at least possible:
Hotel Mae Phim Resort. Quite a big hall, swimming pool and sauna. Prices: single visit 250B, 10-visit series ticket 1800B, one month 2500B. Longer-term tickets are also on sale, map link, you can find photos from hotel's website.
Hotelli Grand Blue. Smaller hall, swimming pool and sauna. Offer price 1/2023 90B/day, 999B/month.
Carma Fitness Ban Phe. Relatively large hall, monthly ticket 900 Bath, map link.
The nearest tennis court is located about 500 meters from the Marriot hotel, in a place called Stella Maris (map link). The price is 250 Bath/hour.